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2kW SmartPie

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Lollandster:
Hi, I did some modifications to my SmartPie and I thought someone else might be interested in the results.

Due to some problems with my internal controller (it stopped working) I ordered a new one, a Lyen 9 Fet. The new controller can do 85v at 30amps and I didn't see a reason why I wouldn't try to max it.

I bought four 5s lipos and connected them to make 20s with a "off the charger" voltage of 84 volts. You can see the test run here: http://youtu.be/n-EuvWoCess

I had a maximum of 22amps and 1750watts showing on my CycleAnalyst. I don't have an accurate shunt measurement for my current shunt and I believe the real wattage is higher than my reading. I'll connect my accurate 1mohm shunt later and get a real reading.

I used GPS to get a accurate speed reading on my test drive and I clocked 45km/h on the straights and 55km/h down hill. I did a run together with a pal of mine that has the MagicPie 3 unmodified (controller set to 30amps) with 16s LiFePO4 (~58v off the charger) and I had no problems accelerating away from him and hitting higher top speeds. Both where running on studded tires. I expect slightly higher top speeds on slicker tires.

I have installed a temperature probe right next to one of the coils and I got a temperature reading of 80C after gunning full throttle for about 5 minutes. The temperature sensor is connected to the Cycle Analyst and the throttle will automatically back off if I reach 99C. It was -8C outside so getting the coils that hot that fast is evidence that this isn't power levels the SmartPie is happy with. I won't recommend anyone to use close to 2kW on the SmartPie without a temperature probe.

I have written a lot about the modification on my blog. Feel free to read more there:
http://lollandster.wordpress.com/2012/12/25/modifying-the-smartpie/

atcspaul:
something dosn't sound right. I have a Smart Pie and Magic Pie III. my Magic Pie III with the internal controller I get 45kmh on the flats and down hill I have hit 65kmh.
(actually more like down mountain then hill lol) I know others in the states that get the same results with the mp3.  I would think the higher voltage and better controller would give a lot better results. my smart at 48volts I get 37 to 38 kmh.
in the video it looks like it has amazing torgue. I mean it darn near yanks out of your hand. very impresive

Lollandster:

--- Quote from: atcspaul on January 12, 2013, 04:12:36 PM ---something dosn't sound right. I have a Smart Pie and Magic Pie III. my Magic Pie III with the internal controller I get 45kmh on the flats and down hill I have hit 65kmh.
(actually more like down mountain then hill lol) I know others in the states that get the same results with the mp3.  I would think the higher voltage and better controller would give a lot better results. my smart at 48volts I get 37 to 38 kmh

--- End quote ---
I forgot to mention that both of us where running on very knobby studded tires (winter time here). I have included that vital info in the OP now.

atcspaul:
by the looks of the video it will stand on end if you start out with full throttle. good fun for sure

Lollandster:

--- Quote from: atcspaul on January 12, 2013, 04:21:41 PM ---by the looks of the video it will stand on end if you start out with full throttle. good fun for sure

--- End quote ---
No chance to get the bike up on one wheel. The torque is probably lower than on the MP3, but the acceleration is better. With the wheel off the ground the wheel accelerates up to 75kph almost instantly so it looks very impressive, but in the real world you can't feel the power until you hit about 10kph, below that it is not impressive, I can't even do burnouts on gravel.

I tried the bike off-road today since off-roading is the reason I want more power. Even with my studded tires with low air pressure the forest roads where way too slippery, it was actually safer to stay on the bike than try walking. I did however get to try some anyway and there was a big difference. At very low speed the extra watts does make a difference compared to 15a original, but it wasn't much better than setting the internal controller to 30 amps, I'm guessing exactly the same. But as soon as I gather a little speed this thing flies. I found some fields without too much ice and it feels like the acceleration never stops (at least my nerves stops before the acceleration does).

After a little playing around I got back to the street and test the power usage on sustained max speed on close to level ground and it shows 1100 to 1200 watts. I'm not sure how much my tires play a role here, but it looks like it is very ineffective and power draining. Can anyone quote the power usage to maintain ~50kph with a MagicPie? After finishing the short ride I had used 1.1 Ah (about 80wh) and the coil temperature was 109'C (ambient was -8'C) The motor was quite warm to the touch.

I think I'll use 10s2p in the future and not 20s1p. The motor gets too warm and uses way too much power at high speed. I might end up buying a slow wind BPM for off-raoding. Top speed isn't important to me, fuel economy is.

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